New schemes that will enable the ability to send more and more bits through a fixed bandwidth communication channel without substantially increasing the transmit power will always be beneficial. Multiple Input Multiple Output (MIMO) is an upcoming technology that uses multiple transmit and receive antennas to send higher amounts of data while keeping the transmit power and bandwidth constant.
FIG. 1 depicts a generic (2×2) MIMO communication system. The transmitter is transmitting independent data {s1, and s2} on the two antennas. At each of the receivers a composite signal is received, which in this simple 2×2 case is shown in the equations below.r1=s1h11+s2h12 r2=s1h21+s2h22 
From the two equations above it can be seen that the two independent sets of data have been acted upon by the channel to create a combined signal at each of the receiver. Conventional communication systems treat this combined signal as interference from which the individual signals cannot be recovered. MIMO uses a different signal processing technique. By treating the channel as a matrix it solves the above two equations with two unknowns to extract the transmitted data s1 and s2. In order to successfully extract s1 and s2 we have to estimate hij and create the channel matrix H.
  H  =      [                                        h            11                                                h            12                                                            h            21                                                h            22                                ]  
Multiplying r1 and r2 with the inverse of H gives us an estimate of s1 and s2. MIMO systems work by adding multiple spatial paths between the transmitter and the receiver. In order for the channel matrix H to be invertible the environment has to be rich in multipath. In a scattering rich channel (multipath rich) several concurrent spatial data pipes are created within the same bandwidth leading to higher transmission capacity between the transmitter and the receiver.
Accordingly, there is a need for a method to artificially create a dynamic multipath rich environment. There is also a need for being able to control the amount of multipath.
The techniques herein below extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.